Hey everybody, I have a Cat 259D, and the A/C is blowing hot air. I hooked up gauges, and it definitely has refrigerant, but I see the cllpress or pumps for a few seconds, the erasure roses, and it cuts out. It will do it again in a few seconds. The belt is spinning the whole time, but the clutch only starts spinning for a few seconds and then kicks out again, the same timing as when you can see the compressor start pumping on the gauges. Anybody have any idea? Thanks
Does your low side pressure drop below the cutout point? About 15 psi or so
No it never did. I can remember the exact psi, but it is equalized far above that. Then it starts pumping for a few seconds, begins to climb (low side only) and then falls again
Low side will drop, not climb when it starts pumping. . .. You will need to verify power to the pressure switches, then figure out where it is cutting out. Could be thermostat, pressure switch, hi Amp draw on compressor clutch tripping something.. . Post a serial number so the Cat guys can chime in.
Serial number is CAT0259DTFTL05998 The low pressure and high pressure switches both had continuity. I’m guessing they’re both normally closed, correct? And then open when experiencing high or low pressure?
It is apparently a bit more complicated than that for the HP cutout switch. See below. The HP switch is normally open. With rising pressure in the system it closes at 40psi and remains closed up to 405 psi, when it goes open again. If the switch is closed in an operating system with falling pressure it stay closed down to 25psi, where it goes open. 34.5 kPa for the LP Switch is about 5psi If the switch is closed
Sounds like its low on freon.
Anybody have schematics for this? I want to see where the thermostat wiring goes to. Is it possible the thermostat os intermittently sending voltage? Or maybe the clutch is overamping? I will run it and check the high pressure switch and see if it os opening and closing when it should be. I believe the pressures never went below 40 psi but I will double check.
does anybody know where the resting pressure should be for the low side?
At rest should be same as high. .. . Possibly 40 to 80 psi. ?
Check your messages.